1. Field of the Invention
The present invention relates generally to hydraulic dampers. In particular, this invention is concerned with a twin tube strut having a reciprocating piston and piston rod mounted in a fluid-filled inner cylinder which provides variable damping dependent upon the rotation of an attached wheel assembly.
2. Brief Description of the Related Art
Hydraulic dampers, including shock absorbers and struts, are well-known in vehicle suspension systems. The rate of damping of a hydraulic strut is often tuned by a piston valving assembly and/or base valve assembly. Conventional piston and base valving assemblies employ various disk packs and spring-biased blow-off elements. During compression and rebound strokes of a strut, fluid flow through these valving assemblies determines the type of damping characteristic produced by the strut.
Many constructions have been developed to provide variable damping. In particular, it is well-known to provide a rotatable plate in a piston valving assembly to change the size of an orifice or other element to alter fluid flow through a piston valving assembly. Oftentimes, an electric motor is used to rotate a valve plate in a piston assembly.
The art continues to seek improvements. It is desirable to provide a variable damping strut to perform under different driving conditions. In particular, during straight-ahead motion of a vehicle, a "soft" ride increases the comfort of passengers. During a steering motion when the vehicle wheels are turned, a "firm" damping rate provides greater control of the vehicle. It is desirable to provide a strut which can vary the damping rate dependent upon these driving conditions.